Feature request: Unity build

[Milerius]

Is your feature request related to a problem? Please describe.

with CMake we have this fantastic feature: https://cmake.org/cmake/help/latest/prop_tgt/UNITY_BUILD.html

which at work help us to reduce the compilation time by ~4-5 times, do you think it's possible to have the equivalent ?

Describe the solution you'd like

Same unity build as CMake with possibility to exclude some source from the unity such as (obj-c) file

Describe alternatives you've considered

Using CMake

[waruqi]

This seems to be a great optimization feature, and I will consider supporting this feature in future versions.

But the current 2.3.9 version focuses on improving package management, so I do not plan to add support for it in 2.3.9 version.

[xq114]

https://github.com/Kitware/CMake/blob/aa283fdba161eb458b02caaa9f0c32d97c648d6f/Source/cmLocalGenerator.cxx#L2915-L2982

This file contains the implementation detail for unity build mode: writing a file like

// unity_block_1.c
#define <UNIQUE_ID> <file1_c_md5>
#include "file1.c"
#undef <UNIQUE_ID>
#define <UNIQUE_ID> <file2_c_md5>
#include "file2.c"
#undef <UNIQUE_ID>
...

There are some rules for files to be included, for instance, any files with different compiler definitions can't be included in one block.

For information about UNIQUE_ID, see
https://cmake.org/cmake/help/latest/prop_tgt/UNITY_BUILD_UNIQUE_ID.html

[waruqi]

I have supported it. #1749

C Unity

add_rules("c.unity_build")

C++ Unity

add_rules("c++.unity_build")

Batch mode (default mode)

We can use batchsize set the batch size. It will merge a single file if no given batchsize.

target("test")
    set_kind("binary")
    add_includedirs("src")
    add_rules("c++.unity_build", {batchsize = 2})
    add_files("src/*.c", "src/*.cpp")

Group mode

target("test")
    set_kind("binary")
    add_rules("c++.unity_build", {batchsize = 0}) -- disable batch mode
    add_files("src/*.c", "src/*.cpp")
    add_files("src/foo/*.c", {unity_group = "foo"})
    add_files("src/bar/*.c", {unity_group = "bar"})

Batch and group mode

target("test")
    set_kind("binary")
    add_includedirs("src")
    add_rules("c++.unity_build", {batchsize = 2})
    add_files("src/*.c", "src/*.cpp")
    add_files("src/foo/*.c", {unity_group = "foo"})
    add_files("src/bar/*.c", {unity_group = "bar"})

Ignore the given files

target("test")
    set_kind("binary")
    add_includedirs("src")
    add_rules("c++.unity_build", {batchsize = 2})
    add_files("src/*.c", "src/*.cpp")
    add_files("src/test/*.c", {unity_ignored = true}) -- ignore these files

$ xmake -r
[ 11%]: ccache compiling.release build/.gens/test/unity_build/unity_642A245F.c
[ 11%]: ccache compiling.release build/.gens/test/unity_build/unity_bar.c
[ 11%]: ccache compiling.release build/.gens/test/unity_build/unity_73161A20.c
[ 11%]: ccache compiling.release build/.gens/test/unity_build/unity_F905F036.c
[ 11%]: ccache compiling.release build/.gens/test/unity_build/unity_foo.c
[ 11%]: ccache compiling.release build/.gens/test/unity_build/unity_642A245F.cpp
[ 77%]: linking.release test
[100%]: build ok

Unique ID

target("test")
    set_kind("binary")
    add_includedirs("src")
    add_rules("c++.unity_build", {batchsize = 2, uniqueid = "MY_UNITY_ID"})
    add_files("src/*.c", "src/*.cpp")

[Milerius]

That's nice ! Thanks a lot

[waruqi]

I have supported Unique ID.